I am going to go a bit smaller...
My current favorite 6mm is the 6X45. I have an AR with a 20" Black Hole Weaponry barrel on it that is a great coyote or deer gun. I was able to get a very good deal on a bunch (10 boxes) of the now discontinued 80 grain Sierra SSP (single-shot pistol) bullets. They shoot great out of the AR, I am able to get good velocity with them and they perform very well on game. When those are gone, I won't hesitate to use the 90 grain Nosler BTs or the 92 grain Cavity Back MKZs. For the type of hunting that I do (mostly small plot or field corners for meat deer), it is just about the perfect round. Add a suppressor and I can watch the bullet impact through the scope.
I like it so much that I just picked up a Remington SPS Varmint in .223 for cheap with the intention of making it into a lightweight 6X45 repeater that I can throw the suppressor on an put into the hands of my young nephews for deer hunting.
